Hopf bifurcation in an age-structured predator-prey system with Beddington-DeAngelis functional response and constant harvesting.

In this paper, an age-structured predator-prey system with Beddington-DeAngelis (B-D) type functional response, prey refuge and harvesting is investigated, where the predator fertility function f(a) and the maturation function ß ( a ) are assumed to be piecewise functions related to their maturation period τ . Firstly, we rewrite the original system as a non-densely defined abstract Cauchy problem and show the existence of solutions. In particular, we discuss the existence and uniqueness of a positive equilibrium of the system. Secondly, we consider the maturation period τ as a bifurcation parameter and show the existence of Hopf bifurcation at the positive equilibrium by applying the integrated semigroup theory and Hopf bifurcation theorem. Moreover, the direction of Hopf bifurcation and the stability of bifurcating periodic solutions are studied by applying the center manifold theorem and normal form theory. Finally, some numerical simulations are given to illustrate of the theoretical results and a brief discussion is presented.

Biomechanical Evaluation of 2 Endoscopic Spine Surgery Methods for Treating Lumbar Disc Herniation: A Finite Element Study.

OBJECTIVE: This study aimed to evaluate the effects of 2 endoscopic spine surgeries on the biomechanical properties of normal and osteoporotic spines. METHODS: Based on computed tomography images of a healthy adult volunteer, 6 finite element models were created. After validating the normal intact model, a concentrated force of 400 N and a moment of 7.5 Nm were exerted on the upper surface of L3 to simulate 6 physiological activities of the spine. Five types of indices were used to assess the biomechanical properties of the 6 models, range of motion (ROM), maximum displacement value, intervertebral disc stress, maximum stress value, and articular protrusion stress, and by combining them with finite element stress cloud. RESULTS: In normal and osteoporotic spines, there was no meaningful change in ROM or disc stress in the 2 surgical models for the 6 motion states. Model N1 (osteoporotic percutaneous transforaminal endoscopic discectomy model) showed a decrease in maximum displacement value of 20.28% in right lateral bending. Model M2 (unilateral biportal endoscopic model) increased maximum displacement values of 16.88% and 17.82% during left and right lateral bending, respectively. The maximum stress value of L4-5 increased by 11.72% for model M2 during left rotation. In addition, using the same surgical approach, ROM, maximum displacement values, disc stress, and maximum stress values were more significant in the osteoporotic model than in the normal model. CONCLUSION: In both normal and osteoporotic spines, both surgical approaches were less disruptive to the physiologic structure of the spine. Furthermore, using the same endoscopic spine surgery, normal spine biomechanical properties are superior to osteoporotic spines.

Antibody responses to an inactivated SARS-CoV-2 vaccine in individuals aged from 50 to 102 years.

Objectives: To assess antibody responses to an inactivated SARS-CoV-2 vaccine in individuals aged 50 and older. Methods: We conducted a post-market cross-sectional seroepidemiology study. We recruited 4,632 vaccinated individuals aged 50 and older, measured their total serum SARS-CoV-2-specific antibody (TA), and collected correlates. The primary outcome was the geometric mean titer (GMT) of TA, and the secondary outcome was the decline of TA with age. Univariate, bivariate, and multivariate analyses were used to examine the associations of the TA GMT with age, and trend analyses were used to test whether their associations were significant. Results: All participants had a detectable TA, which was generally at a low level across all age groups. The TA GMT (95% CI) in AU/mL was 3.05 (2.93, 3.18); the corresponding arithmetic mean (95% CI) was 17.77 (16.13, 19.42) in all participants and 4.33 (3.88, 4.84), 3.86 (3.49, 4.28), 3.24 (2.92, 3.59), 2.77 (2.60, 2.96), and 2.65 (2.48, 2.83) in the age groups of 50-54, 55-59, 60-64, 65-74, and 75 years or older, respectively. The TA GMT decreased with age with a P trend < 0.001. The TA GMT was significantly lower in those with hypertension or diabetes compared to those with neither. Conclusion: The inactivated SARS-CoV-2 vaccine is effective in individuals aged 50 and older. This is the first study that has found an inverse dose-response relationship between ages and the low-level TAs. Older people, especially those with chronic diseases, should get the SARS-CoV-2 vaccine, and their vaccination frequency, dose, and method may need to be different from those of younger people.

A mathematical model reveals the influence of NPIs and vaccination on SARS-CoV-2 Omicron Variant.

An SVEIR SARS-CoV-2 Omicron variant model is proposed to provide some insights to coordinate non-pharmaceutical interventions (NPIs) and vaccination. Mathematically, we define the basic reproduction number R 0 and the effective reproduction number R e to measure the infection potential of Omicron variant and formulate an optimal disease control strategy. Our inversion results imply that the sick period of Omicron variant in the United States is longer than that of Delta variant in India. The decrease in the infectious period of the infection with infectiousness implies that the risk of hospitalization is reduced; but the increasing period of the infection with non-infectiousness signifies that Omicron variant lengthens the period of nucleic acid test being negative. Optimistically, Omicron's death rate is only a quarter of Delta's. Moreover, we forecast that the cumulative cases will exceed 100 million in the United States on February 28, 2022, and the daily confirmed cases will reach a peak on February 2, 2022. The results of parameters sensitivity analysis imply that NPIs are helpful to reduce the number of confirmed cases. In particular, NPIs are indispensable even if all the people were vaccinated when the efficiency of vaccine is relatively low. By simulating the relationships of the effective reproduction number R e , the vaccination rate and the efficacy of vaccine, we find that it is impossible to achieve the herd immunity without NPIs while the efficiency of vaccine is lower than 88.7 % . Therefore, the herd immunity area is defined by the evolution of relationships between the vaccination rate and the efficacy of vaccine. Finally, we present that the disease-induced mortality rate demonstrates the periodic oscillation and an almost periodic function is deduced to match the curve. A discussion completes the paper.

Large phonon thermal Hall conductivity in the antiferromagnetic insulator Cu3TeO6.

Phonons are known to generate a thermal Hall effect in certain insulators, including oxides with rare-earth impurities, quantum paraelectrics, multiferroic materials, and cuprate Mott insulators. In each case, a special feature of the material is presumed relevant for the underlying mechanism that confers chirality to phonons in a magnetic field. A fundamental question is whether a phonon Hall effect is an unusual occurrence-linked to special characteristics such as skew scattering off rare-earth impurities, structural domains, ferroelectricity, or ferromagnetism-or a much more common property of insulators than hitherto believed. To help answer this question, we have turned to a material with none of the previously encountered special features: the cubic antiferromagnet Cu3TeO6. We find that its thermal Hall conductivity [Formula: see text] is among the largest of any insulator so far. We show that this record-high [Formula: see text] signal is due to phonons, and it does not require the presence of magnetic order, as it persists above the ordering temperature. We conclude that the phonon Hall effect is likely to be a fairly common property of solids.

Comparison of Pharmacokinetics and Tissue Distribution Characteristics of Three Diterpenoid Esters in Crude and Prepared Semen Euphorbiae.

BACKGROUND: Semen Euphorbiae (SE) and Semen Euphorbiae Pulveratum (SEP) have a long history of medicinal use. SEP is the processed product of SE; both ancient and modern studies have shown that SEP has a lower toxicity compared to SE. To clarify the influence of processing on the pharmacological properties of SE and SEP, a study was carried out to compare the pharmacokinetics and distribution characteristics of three active compounds after oral administration of SE and SEP extracts. METHODS: A UPLC-MS/MS method was established to simultaneously determine the contents of Euphorbia factors L1, L2, and L3 in rat plasma and mouse tissues after an oral administration of crude and processed SE with approximately the same dosage. Plasma and heart, liver, spleen, lung, kidney, and colon tissue samples were treated with ethyl acetate and separated by gradient elution on a C18 column with a mobile phase of 0.1% formic acid and methanol. RESULTS: The established method had good selectivity, linear range, accuracy, precision, stability, matrix effect, and extraction recovery. The area under the concentration time curve, time to maximum concentration, maximum concentration, half-life of elimination, and mean retention time of plasma samples in SEP-treated group decreased, and the clearance in SEP-treated group increased. Moreover, the active component concentrations in colon, liver, and kidney tissues were more followed by those in the heart, lungs, and spleen. CONCLUSION: These results indicate that the processing could influence the pharmacokinetics and tissue distribution of Euphorbia factors L1, L2, and L3 after oral administration of crude and processed SE. The data obtained may lay a foundation for the clinical use of SE and for further study on the processing mechanism of SE.

Antiferromagnetic Order and Spin-Canting Transition in the Corrugated Square Net Compound Cu3(TeO4)(SO4)·H2O.

Strongly correlated electrons in layered perovskite structures have been the birthplace of high-temperature superconductivity, spin liquids, and quantum criticality. Specifically, the cuprate materials with layered structures made of corner-sharing square-planar CuO4 units have been intensely studied due to their Mott insulating ground state, which leads to high-temperature superconductivity upon doping. Identifying new compounds with similar lattice and electronic structures has become a challenge in solid-state chemistry. Here, we report the hydrothermal crystal growth of a new copper tellurite sulfate, Cu3(TeO4)(SO4)·H2O, a promising alternative to layered perovskites. The orthorhombic phase (space group Pnma) is made of corrugated layers of corner-sharing CuO4 square-planar units that are edge-shared with TeO4 units. The layers are linked by slabs of corner-sharing CuO4 and SO4. Using both the bond valence sum analysis and magnetization data, we find purely Cu2+ ions within the layers but a mixed valence of Cu2+/Cu+ between the layers. Cu3(TeO4)(SO4)·H2O undergoes an antiferromagnetic transition at TN = 67 K marked by a peak in the magnetic susceptibility. Upon further cooling, a spin-canting transition occurs at T* = 12 K, evidenced by a kink in the heat capacity. The spin-canting transition is explained on the basis of a J1-J2 model of magnetic interactions, which is consistent with the slightly different in-plane superexchange paths. We present Cu3(TeO4)(SO4)·H2O as a promising platform for the future doping and strain experiments that could tune the Mott insulating ground state into superconducting or spin liquid states.

Exercise profile and effect on growth traits, carcass yield, meat quality, and tibial strength in Chinese Wannan chickens.

The aim of the study was to understand the dynamic changes in daily step counts (DSC) during the development of chickens and to further explore the effects of exercise on the growth performance, carcass yield, meat quality, and tibial strength of cocks. A total of 600 (half male and half female) 1-day-old Wannan chickens with similar hatching weights were raised under the same rearing conditions. All birds were wing banded and housed in identical cages for from 1 to 8 wk in the experimental poultry house. The dimensions of the cages were 70 × 70 × 40 cm (length × width × height). At the age of 9 to 16 wk, these birds were reared in indoor pens (2 m × 2 m, 1,000 cm2 per bird). In addition, they also had a free-range grass paddock (20 m × 30 m, 1 m2 per bird). The DSC of male and female Wannan chicks were recorded from 70 to 112 d by using a pedometer. At 112 d of age, based on the average DSC, birds were divided into groups representing the highest (HS), medium, and lowest (LS) number of step groups. Fifteen cocks from each group were selected for subsequent experiments. Compared with the LS group, the HS group displayed higher tibial strength (P = 0.025) and lower BW, cooking loss (P = 0.014), shear force (P = 0.023), and drip loss (P = 0.008). The DSC had no effects on the female BW or male carcass parameters. There was no significant change in the DSC of all birds from 70 to 112 d. However, male chickens took more steps than females at 15 (P = 0.025) and 16 (P = 0.012) week of age. In conclusion, the effects of the DSC on the BW of Wannan chickens depend on sex, and enhanced exercise could improve the meat quality and tibial strength of cocks.

Colossal Magnetoresistance without Mixed Valence in a Layered Phosphide Crystal.

Materials with strong magnetoresistive responses are the backbone of spintronic technology, magnetic sensors, and hard drives. Among them, manganese oxides with a mixed valence and a cubic perovskite structure stand out due to their colossal magnetoresistance (CMR). A double exchange interaction underlies the CMR in manganates, whereby charge transport is enhanced when the spins on neighboring Mn3+ and Mn4+ ions are parallel. Prior efforts to find different materials or mechanisms for CMR resulted in a much smaller effect. Here an enormous CMR at low temperatures in EuCd2 P2 without manganese, oxygen, mixed valence, or cubic perovskite structure is shown. EuCd2 P2 has a layered trigonal lattice and exhibits antiferromagnetic ordering at 11 K. The magnitude of CMR (104 %) in as-grown crystals of EuCd2 P2 rivals the magnitude in optimized thin films of manganates. The magnetization, transport, and synchrotron X-ray data suggest that strong magnetic fluctuations are responsible for this phenomenon. The realization of CMR at low temperatures without heterovalency leads to a new regime for materials and technologies related to antiferromagnetic spintronics.

Revisiting the evolutionary history of domestic and wild ducks based on genomic analyses.

Although domestic ducks have been important poultry species throughout human history, their origin remains enigmatic, with mallards and/or Chinese spot-billed ducks being proposed as the direct wild ancestor(s) of domestic ducks. Here, we analyzed 118 whole genomes from mallard, Chinese spot-billed, and domestic ducks to reconstruct their evolutionary history. We found pervasive introgression patterns among these duck populations. Furthermore, we showed that domestic ducks separated from mallard and Chinese spot-billed ducks nearly 38 thousand years ago (kya) and 54 kya, respectively, which is considerably outside the time period of presumed duck domestication. Thus, our results suggest that domestic ducks may have originated from another wild duck population that is currently undefined or unsampled, rather than from present-day mallard and/or Chinese spot-billed ducks, as previously thought. Overall, this study provides new insight into the complex evolution of ducks.

A stage-structured SEIR model with time-dependent delays in an almost periodic environment.

In this paper, we propose and investigate an almost periodic SEIR model with stage structure and latency, in which time-dependent maturation and incubation periods are incorporated. Two threshold parameters for the persistence and extinction of population and disease are introduced: the basic reproduction ratio $\hat{R}_{0}$ for population and the basic reproduction ratio $R_{0}$ for disease. If $\hat{R}_{0}<1 the="" population="" extinction="" state="" is="" globally="" attractive="" in="" the="" case="" where="" hat="" r="" _="" 0="">1$, it is shown that the disease tends to die out if $R_{0}<1 while="" remains="" persistent="" if="" r_="" 0="">1$. By virtue of numerical simulations, we verify the analytic results and investigate the effects of the fluctuations of maturation and incubation periods on disease transmission.

A potential drug combination of omeprazole and patchouli alcohol significantly normalizes oxidative stress and inflammatory responses against gastric ulcer in ethanol-induced rat model.

Omeprazole (OME) is a representative of proton pump inhibitors and widely used in anti-ulcer treatment. However, OME may cause some inevitable side effects and the long-term consequences of OME could increase the risk of diarrhea. Patchouli Alcohol (PA), the main extract of Pogostemonis Herba, have demonstrated benefits in treating gastric ulcer (GU) with low toxicity. The present study aimed to investigate the synergistically protective effects of OME and PA against ethanol-induced GU in rats to study the involvement of antioxidant and anti-inflammatory activities. Moreover, the anti-apoptosis, anti-oxidant and anti-inflammatory effects in H2O2-induced gastric epithelial cells (GES-1) and LPS-induced RAW264.7 cells were determined, as well as the modulation of signaling proteins. The results demonstrated that PA alone or combined with OME provided remarkable benefits by reducing ulcer areas, modulating oxidant stress and inflammatory factors and the therapeutic efficacy was showed to be dose-dependent, which were partly superior to that of high-dose OME only. Additionally, co-treated regimen could superiorly down-regulate cell apoptosis and regulate the levels of oxidant activities and inflammatory cytokines on H2O2-induced GES-1 cells and LPS-induced RAW264.7 cells, which involved with cleaved caspase 3, Bcl-2 and BAX protein expressions and MAPK pathway. We provided a new understanding that the combination of OME and PA possessed gastroprotective effects on modulating cell apoptosis, antioxidant stress and anti-inflammatory responses against GU. Therefore, PA was inferred to take a potential and critic role in gastric mucosa protection.

Capsaicin derivatives with nitrothiophene substituents: Design, synthesis and antibacterial activity against multidrug-resistant S. aureus.

To address the emergency caused by multi-drug resistant Staphylococcus aureus, a series of novel capsaicin derivatives with nitrothiophene substituents have been designed and evaluated for the antibacterial activities against S. aureus Newman and multidrug-resistant strains (NRS-1, NRS-70, NRS-100, NRS-108, and NRS-271). The structure-activity relationship was further revealed. Compound 13c, 13f, and 13g were highly active against staphylococcal growth, with minimal inhibition concentration (MIC) values of 0.39-1.56 µg/mL. The oxadiazole-derived compound 21, a bioisostere of ester 13f, is the most potent candidate for anti-growth of five multidrug-resistant S. aureus strains with MICs of 0.20-0.78 µg/mL, which is more active compared with vancomycin in vitro. Notably, these anti-staphylococcal compounds are much less cytotoxic to the normal kidney epithelial cell line (HK293T).

Chemical constituents from acid hydrolyzates of Panax quinquefolius total saponins and their inhibition activity to α-glycosidase and protein tyrosine phosphatase 1B.

Objective: To investigate the hypoglycemic components from the acid hydrolyzates of Panax quinquefolius total saponins, and screen the active compounds by in vitro inhibitory activities to α-glycosidase enzymes and protein tyrosine phosphatase-1B (PTP1B). Methods: The hydrolyzates were chromatographed repeatedly over silica gel column, and the structures of the compounds were determined by means of NMR. The in vitro bioassay was performed through the inhibitory effects on α-glucosidase or/and PTP1B. Results: Eight compounds were isolated, which identified as 20(S)-panaxadiol (1), (20S,24R)-dammarane-20,24-epoxy-3ß,6α,12ß,25-tetraol (2), 20(R)-dammarane-3ß,12ß,20,25-tetraol (3), 20(S)-dammarane-3ß,6α,12ß,20,25-pentol (4), 20(R)-dammarane-3ß,12ß,20,25-tetrahydroxy-3ß-O-ß-d-glucopyranoside (5), ß-sitosterol (6), oleanolic acid (7) and 20(S)-protopanaxadiol (8). Compound 5 was ginseng triterpenoid isolated from the acid hydrolysates of total saponins from P. quinquefolius for the first time. In this paper, the possible in vitro inhibitory activities were investigated. Compound 5 exhibited significantly inhibitory activity against α-glucosidase, and the IC50 value [(0.22 ± 0.21) µmol/L] was about 43-fold lower than positive control. For the PTP1B inhibition assay, compound 5 indicated the strongest inhibitory effect with IC50 of (5.91 ± 0.38) µmol/L, followed by compound 4 with IC50 of (6.21 ± 0.21) µmol/L, which were all showed competitive inhibitory pattern by using a Lineweaver-Burk plot. Conclusion: These results supported the potential application of dammaranes from acid hydrolyzates of P. quinquefolius total saponins can be used as ingredients of ancillary anti-diabetic agent or functional factor.

An almost periodic Ross-Macdonald model with structured vector population in a patchy environment.

An almost periodic Ross-Macdonald model with age structure for the vector population in a patchy environment is considered. The basic reproduction ratio [Formula: see text] for this model is derived and a threshold-type result on its global dynamics in terms of [Formula: see text] is established. It is shown that the disease is uniformly persistent if [Formula: see text], while the disease will die out if [Formula: see text]. Numerical simulations show that the biting rate greatly affects the disease transmission, and human migration sometimes could reduce the transmission risk. We further obtain a condition numerically to determine whether a control strategy on migration is necessary. Moreover, numerical results indicate that prolonging the length of maturation period of vector is beneficial to the disease control, and the threshold length of the maturation period for disease outbreak can be computed. Finally, the comparison between the almost periodic and periodic models shows that the periodic model may overestimate or underestimate the disease transmission risk.

Synthesis and anticancer activity of novel 9,13-disubstituted berberine derivatives.

Novel berberine derivatives with disubstituents on positions C9 and C13 were synthesized and evaluated for antiproliferative activities against human prostate cancer cell lines (PC3 and DU145), breast cancer cell line (MDA-MB-231) and human colon cancer cell lines (HT29 and HCT116). All compounds showed significantly enhanced antiproliferative activities compared with berberine. Notably, compound 18e exhibited the strongest cytotoxicity against PC3 cells with an IC50 value of 0.19 µM, and the highest selectivity index (SIPC3 > 20). Further studies showed that 18e could arrest the cell cycle at G1 phase, and significantly inhibit tumor cell colony forming and migration even at low concentrations. Interestingly, 18e could significantly induce cytoplasmic vacuolation, suggesting a different mode of action from berberine.

Normal-state properties of the quasi-one-dimensional superconductor Ta4Pd3Te16.

We examined the physical properties of the quasi-one-dimensional superconductor Ta4Pd3Te16 in the normal state by detailed measurements of susceptibility, in-plane anisotropic resistivity, magnetoresistance, Hall resistivity, and Seebeck coefficient. The large Wilson ratio, as inferred from normal-state susceptibility, indicates strong electron-electron interaction. The Hall and Seebeck coefficients show not only significant temperature-dependent behavior, indicating the multiband effect, but also an obvious anomaly around T 1 = 40 K. Analyses of both the Hall resistivity and thermopower using a two-band model indicate that the electrons dominate the electrical transport at low temperatures. Our results imply that it is the quantum fluctuations of the charge order taking place in the temperature range 30-50 K that may result in the abnormal normal-state properties of Ta4Pd3Te16.

Peculiar phase diagram with isolated superconducting regions in ThFeAsN1-x O x.

ThFeAsN1-x O x ([Formula: see text]) system with heavy electron doping has been studied by the measurements of x-ray diffraction, electrical resistivity, magnetic susceptibility and specific heat. The non-doped compound exhibits superconductivity at [Formula: see text] K, which is possibly due to an internal uniaxial chemical pressure that is manifested by the extremely small value of As height with respect to the Fe plane. With the oxygen substitution, the T c value decreases rapidly to below 2 K for [Formula: see text], and surprisingly, superconductivity re-appears in the range of [Formula: see text] with a maximum [Formula: see text] of 17.5 K at x = 0.3. For the normal-state resistivity, while the samples in intermediate non-superconducting interval exhibit Fermi liquid behavior, those in other regions show a non-Fermi-liquid behavior. The specific heat jump for the superconducting sample of x = 0.4 is [Formula: see text], which is discussed in terms of anisotropic superconducting gap. The peculiar phase diagram in ThFeAsN1-x O x presents additional ingredients for understanding the superconducting mechanism in iron-based superconductors.

Traveling wave solutions in a two-group SIR epidemic model with constant recruitment.

Host heterogeneity can be modeled by using multi-group structures in the population. In this paper we investigate the existence and nonexistence of traveling waves of a two-group SIR epidemic model with time delay and constant recruitment and show that the existence of traveling waves is determined by the basic reproduction number [Formula: see text] More specifically, we prove that (i) when the basic reproduction number [Formula: see text] there exists a minimal wave speed [Formula: see text] such that for each [Formula: see text] the system admits a nontrivial traveling wave solution with wave speed c and for [Formula: see text] there exists no nontrivial traveling wave satisfying the system; (ii) when [Formula: see text] the system admits no nontrivial traveling waves. Finally, we present some numerical simulations to show the existence of traveling waves of the system.